Controlling system for electric hoists.



FLT. SMITH.

CONTROLLING SYSTEM FOR ELECTRIC HOISTS.

' APPLICATION FILED APR-5, 1911.

m M 2H m a w, 0m dw m2 n m Mm P JMM M w fl 6 3 1 m 1 o P; I. SMITH.CONTROLLING SYSTEM FOR ELECTRIC HOISTS.

APPLICATION FILED APR. 5. 1911.

2 SHEETS-SHEET 2,

Patented 0011.29, 1912.

v UNITED STATES PATENT OFFICE.

FRANK I. SMITH, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOIR. TO OTIS ELEVATORCOMPANY, 'OFJERSEY CITY, NEW JERSEY, A CORPORATION 01 NEW JEBSET.

To all whom it may concern:

CONTROLIIING SYSTEM FOR ELECTRIC HOISTS.

Be'it known that I, FRANK I. S ITH, a

. citizen of the United States, residing at of motors used forPittsburgh, in the county of Allegheny and State of Pennsylvania, haveinvented a new and useful Improvement in Controlling Systems forElectric Hoists, of which'thefollowing is a specification.

-- I My invention relates to motor controlling apparatus, andparticularly to the control furnace hoists.

()ne object of my invention is automatically to reduce the speed of thehoisting car or bucket as the latter approaches its limits of travel.

A further objeotis the provision of means for independently controllingand regulat-,

able toefi'ect a slow-down of the driving. motor before applying the.brake to stop the machine. Inthe familiar case of vertical riseelevatorssuch as are used in modern oflice buildings for conveying passengers,etc, plOVlSlOIllS made for slowing down the motor just previoustostopping so that the elevator car will gently and smoothlystop at anydesiredt landing without jar or dis-v comfort to the passengers. .Inorder to effect this slow down before stopping where the elevator'isoperated by an electric motor it iscustomary to employ one or moreelectro-miignets which are arranged to be: op-

both, thereby causing the motor torun at reduced speed just before astop ismade. Vhile such an arrangementis widely used and its operationanswers very wellfwhere the elevator is of the vertical rise there arecertain difficulties encountere 'wh operating skips for blast eratedatthe proper time to vary the-motorcurrent or increase. the field strengthor that the tendency en it is desired it() use such an arrangement for,effecting :a :slow *down of the hOISt'HIQ motor Specification of LettersPatent. f tg t o n 29, 1912, Application filed April 5, 1911 Serial No;619,061.

lower limit of travel, and seldom if ever stopped at tin-intermediatepoint. Further .more it has been found necessary to effect a diflerentslow-down .at the top of the incline than that at the bottom, for thereason that -in a furnace hoist, the empty bucket may be rapidly sloweddown near the bottom of the hoist, but the heavily loadedfbuck etat thetop of the hoist must be slowed. down much more carefully .and slowl thebucket may swing violently rom' side to side and this has been known todo great damage; moreover, much time might be lostin waiting-for theoscillations to die out so thatthe bucket can be centered ,over the hellof the furnace.

While, as before stated, the usual slowdown for vertical rise elevatorsis the same no matter where the car may be or in what direction it istraveling, it is. readily seen that in a blast furnace hoist provisionshould be made seas to effect a different slow down at the top andbottom limits. My invention contemplates means for doing this in asimple and effective manner an furthermorein a way whichwill be entirelyautomatic and dependent upon the load and speed of the bucket.

Referring to Fig. 1, Adesi nates a blast furnace which supplied wit ore,etc, at the top ,iafter the usual manner lg means of a bucket B which issuspended. om a carriage H adapted to travel over the inclined rails T.

zontaL. S designates the power house which contains the motor M and thecontrolling switches E and C. F is the driving cable otherwise which issecured to the carriage and leads I over suitable guide sheaves I and Dand is driven by the motor M. This arrangement I of inclined hoist railsis common to the ma- Qjonity of blast. furnaces and it will be seen forthe bucket to swing due to .a change in speed at the .lower curveisnnotinearly so great as'it wouldfbe at the upper curved portion.Moreover, while the portion of the rail from the summit of the curve tothe furnace may be substantially horizontal, its general direction isdownward the bell; the effect of this isthat not only must the skip beproperly retarded at the summit in its ascent up the incline, so as tohave it eventually stop and center over the bell, but the.skip must besuitably held back if necessary against any tendency to accelerate afterit has passed the summit or curve. only the differences of conditions atthe top and bottom of the hoist, but the differences as to control, andthe difficulties encountered in securing a perfected control at both.top and bottom. For this reason I have found that it is very desirableto effect a difl'erent speed reduction at the top of the hoist than thatbest adapted for the bottom and I will now describe the apparatus andelectrical circuits associated therewith whereby I effeet this speedreduction.

Referring to Fig. 2, E designates a handswitch for starting, stopping,reversing and accelerating the motor by manual control. C is anautomatically operated controlling switch which effects the proper speedreduction and causes the motor to stop at its' extreme limit of travelin either direction. J designates the usual brake which is used to stopthe motor when the same is disconnected from the main line. B and R arethe motor starting and reversing switches and L is a multiple magnetwhich controls the starting resistance 10 and series field 20.

N is a relay which controls a circuit to the resistance 50 and extrafield 40. 30 designates the shunt field. 60, 70, 80 and 90 are multiplemagnets which control the resistanee 50. With this general description,I will now describe each part in detail, and point out the variouselectrical circuits and their action.

The reversing switches R and R are similar in construction and eachcomprises a magnet winding such as 2 which is adapted, when energized,to raise a core 3 and connected rod 4. The latter carries a pair ofinsulated members or disks 5 and 6 to which are attached contacts 8, 11and 13, 15, respectively. The contacts 8 and 11 are adapted to be raisedinto electrical engagement with stationary contacts 7 and 9, 12,respectively, while the contacts 13 and 15 are normally in engagementwith stationary contacts 14 and 16, respectively, and are raised out ofcontact therewith whenever the magnet winding 2 is energized. Theacceler- All of which go to accentuate not- .nears the bottom of theincline.

controlled by the speed of the motor to short circuit more or less ofthe resistance 50. The magnets and are operated when the loaded bucketapproaches the top of the incline, while the magnets -and operate in asimilar manner when the empty bucket The.construction of these magnetsmay be widely varied but it is desirable to arrange the contactscontrolled thereby in such manner that each one will operate at acertain given strength of magnetism induced by the magnet winding. Oneway of doing this is to adjust the air gap of each contact carryingarmature such as is shown in Patent 677,359, issued to John D. Ihlder onJuly 2, 1901, entitled Electromagnet. It is not considered necessary toillustrate this magnet construction since it is well known in the artand requires no further description. The automatically operated switch Ccomprises a number of conducting segments such as 27, 46 and 28 andinsulating segments such as 33, 36, etc., which may be mounted upon asuitable insulating base and are adapted to be rotated by the motor. Onemethod of doing this is operatively to connect the switch 0 with themotor or other part driven thereby by means of sprocket wheels and chainas shown in Fig. 1, the speed of rotation of the switch segments beingconsiderably less than that of the motor so that the switch segmentswill rotate through an angle of substantially 180 while they motor isdriving the bucket from one end of its travel to the other. Stationarycontacts such as 29, 31 and 32 are normally in engagement with thecontact segments 27 and 28, re-

spectively, while other stationary contacts 1 comprisesa lever 54,operated by the U- shaped lower part of the switch E so as to engage oneof the contacts 55 or .56.

The operation of my invention is as follows: Assuming the and mainsconnectcd to a suitable source of electrical supply, and the loadedbucket B at the bottom of theincline. The lever 49 of switch E ismovedover to the left until the contact 51 comes into electricalengagementwith the fixed contact 52. A circuit is thereby closed to thewinding of the reversin switch B, said circuit being traced as fo lowszof-rom the main by wire 65, to and through the winding 2, wire 66,contacts 31, 29 and con-v tact segment 27 of switch C, wire 67, switchcontacts 52 and 51, and by the wire 68 to the main. The reversing switchR will now operate to close the motor circuit at the wire 72, contacts 8and 7 contacts 7, 8 and 9, 12, and 11 respectively, and to separate thecontacts 13, 14,. and 15, 16, respectively, The motor circuit is nowestablished andimay be traced from the main to the contacts 12 and 11,Wire 69,

contacts 17 and 18 ofreversing switchR,

of reversing switch R, wire 73, armature contacts 78 and 77 of switch R,wire 79 to and through the starting resistance 10' and seriesfieldwinding 20, and by wire 81 to the main, The raising of the reversingswitch R also closes a circuit to the.

. contacts 11, 12, while the extra field circuit is across the motorarmature and may be traced from the brush 74, wire 73, contacts 7 and 8,wire, 72, contacts 18'and 17, wires 69 and 82, through the extra field40 and resistance 50, wire 83, contacts 25 and contact *disk 24 of relayN, wire 79, contacts 77 and 78, and by wire 76 to the armature brush 75.The motor now starts to rotate with the brake released and all fieldwindings excited, the armature current being held in' check by thestarting resistance 10. The closing of the reversing switch R alsoestablishes a circuit to theaccelerating magnet L; this-circuit beingacross the motor armature and including a small portion of the startingresistance 10. As the motor increases its speed andcounter-electro-motive force, the accelerating magnet operates to raiseits contacts 20', 21,22 and23, in

successive order so as gradually to short circuit the startingresistance and series field, thereby allowing the motor to run at normalslow speed, with the'shunt and extra fields excited. The next operationisto give the lever of switch E a further movement to the left until thecontact 51 en ages the contact 53. A circuit is thereby c osed brush 74,to and through the armature to brush 75, wire 76',-

to the relay N and may be traced from the main contacts 12, 11, and 9,wire 71, solenoid of relay N, wire 84, contact 34, contact segment 28,contact 32, contacts 53 and 51, and by wire 68 to the main. The relay Nis thus energized to raise its core and contact plate'24 upwardly,therebyinterrupting the circuit of the extra field at the contact25 and,by thus weakening the motor field excitation allowing the motor to runat normal full speed as a simple shunt machine. As the carriage carryingthe loaded bucket approaches the upper curved portion of the incline thecontrolling switch C which has been rotating in an anti-clockwisedirection, moves the contact segment 28 out of electrical engagementwith the contact 32, so that the latter now rests upon the insulation'38 thereby interrupting the circuitof the relay N. The contact disk 24will now short circuit the contacts 25 and again establish a circuitthrough the extra field winding 40 and resistance 50 and the increase infield strength which necessarily follows will cause the motor to run atreduced speed. As the motor continues to. hoist the bucket at reducedspeed the switch C rotates the contact segment 43 into electricalengagement with the contact 41 thereby establishing a circuit to thewinding 57 of the slowdown magnet 60 which circuit is derived from themotor armature and may be traced as follows: from the armature brush 74,by wire 85,'switch lever 54, contact 55, contact segment 43, contact.41, winding 57, wires 86 and .76 to the armature brush 75.

contacts 59, 61 and 62 in successive order to short-circuit portions ofthe extra field resistance 50 according to the speed and load on themotor. increase the current flowing in the extra field and the motorwill further reduce, its

This operation will tend to.

. The magnet 60 isthen energized to raise its speed. The contact segment43 next engages the contact 39, establishing a circuit to the slow downmagnet 70 which will become energized to raise the contacts 63 and 64and thus short circuit additional portions of the resistance 50resulting in a further speed reduction due to increased field strength.By this time the carriage H has traversed the curved portion at the topof the incline and the bucketis nearly over the top of the furnace. Asthe motor continues to rotate at very slow speed thecontact segment 27passes out of engagement with the contact 31 and the circuit to themagnet winding of the reversingrswitch R is broken and the core 3 andconnected parts drop thereby opening the motor and brake magnet circuitsand connecting the stopresistance 19 across the motor brushes.

This circuit may be traced from the brush.

74, through the resistance'l9, wire 72, contacts 15 and 16, contacts 77and 78, and by stopping by the dynamic action of the rotating armaturegenerating current which is absorbed by the resistance 19, as well asthe retardation due to the application of the friction brake J. Theoperation of the device with a descending bucket is very similar to thatalready described it being merely necessary to move the lever of switchE in a right hand direction, thereby closing a circuit to the reversingswitch It which will establish a circuit to the motor armature in areverse direction than that pointed out in connection with an upwardlymoving bucket. The function of the switch comprising the lever 54: andcontacts 55 and 56 is to open the circuit of the slow-down magnets 60and 70 whenever the switch lever 49 is moved in a right hand direction,and to open the circuit of the slow down magnets 80 and 90 whenever theswitch lever is moved in a left hand direction. The automatic slow downfor a descending bucket is effected by the switch C as before exceptingthat in this case the circuit of the relay N will be interrupted at thecontact 35, while the slow-down magnets 80 and 90 will be energized atthe contacts 48 and 47 and the final stop will occur when the circuit tothe reversing switch R is broken at.

the contact 45. While the switch C will automatically take care of theslowing down and stopping of the bucket at the proper point regardlessof the direction of travel or speed and load, the operator may at anytime stop, slow down or reverse the motor by means of the switch E. I

By the use of separate magnets for effecting the automatic slow down ofthe bucket at the top and bottom of the incline, I am enabled toregulate or adjust the retardation of the motor and load at the top andbottom independently of each other. The manner of effecting this resultis as followsz-The.

contacts of the magnets 80 and 90 are adjusted when the bucket is beinglowered so that the air gap between these contacts and the correspondingcontacts carried upon the magnet frame is such that not only will theyoperate in the proper sequence so as to short circuit successive stepsof resistance but also that each one will respond to a predeterminedamount of magnet strength, which, by virtueof the connections of thesemagnets, namely, across the armature brushes, will be proportional tothe counter-electromotive-force of the motor, or in other words, thespeed. The regulation ofthe slow down at the top of the incline is donein a similar manner by adjusting the contacts 59, 61, etc. of themagnets 60 and 70. It will be not-iced that the connections of thecontacts 63 and 64 alon the resistance 50 are somewhat different romthose of the contacts 63' and 641' The contact 64, which operates onlywhen the bucket is traveling upwardly, is connected so as toshort-circuit the entire resistance 50, so thata very slow speed beforestopping is produced, which is desirable at the upper limit since thebucket is now heavily loaded and may contain, and frequently does, aload of everal tons. It is readily seen that such a load must be handledvery carefully so as to prevent .the bucket from setting up a swingingmotion due to a too rapid change in speed.

While the various contacts of the automatic switch C have been referredto as fixed it is to be understood that they may be and preferably areadjustable about a common center. In this manner the slow down for bothup and down travel may come into operation at any desirable position ofthe bucket while the operation of the magnets 60, 70, 80 and 90 willdepend upon the load and speed of the motor. The number of magnets andcontacts for controlling the slow down resistance 50 maybe varied asdesired, a greater refinement in operation being effected by usin alarge number of contacts and correspon ing steps in resistance.

.VVhile I-have described my invention as particularly adapted to a blastfurnace hoist, it is well ada ted to be used in connection with other'nds of inclined hoists in which it is desired 'to effect, an automaticslow down for both directionsof travel and at the same time permit anadjustment best adapted for the slow-down in. one direction withoutinterfering with the slow down for the opposite direction.

Various changes could readily be made in the apparatus herein shown anddescribed by one skilled in the art without departing independently ofeach other.

2. In a furnace hoistlng apparatus, the

combination with a load carrying device, of

automatic means for reducing the speed of said device-atpredeterminedpoints in its travel, and means for controlling said speed reductionsindependently of see other.

' 3. In a furnace hoisting apparatus, the

combination with a motor andv load carrying device, of means controlledby said motor for reducing the speed of sand device at predeterminedpoints in its travel, and means for controlling said speedreductions-independently of" each other.

at. In afurnace hoisting apparatus",- the combination with a motor andload carrying device, of means'independent of each other forautomatically effecting a. reduction in the speed of the motor and meansfor varymg the actlon of saidspecd reducing means. 5. In a furnacehoisting apparatus,- the combinationwittia motor, of a load carry-. I mgdevice operatively connected therewith, independent means for effectinga reduction in the speed of the motoryandnnean's operated by themotorfor controlling-theoperation of said speed reducing means."

6. In a furnace hoisting apparatus;- the combination with aloadcar1ying=device and a' motor o u-rativcly connected thereto; ofmeans for eontrollm the speedof themotbr in one direction, ad itlonalmeans-for controlling the speed iii-the opposite direction;

and means for controlling the ac'tionof both of said controlling-means.

7. In a furnace hoisting apparatus, the combination with a load carryingdevice and a motor operatively connected thereto,- of means forcontrollingzthe speed'of the motor in one direction, additional meansfor controlling the speed in the opposite direction, and meanscontrolled b. the motor for effecting the operation 0 both of saidcontrolling means.

8. In a furnace hoisting apparatus, the combination with a load carryingdevice and a motor operatively connected therewith, of means separatefrom each other for effecting a reduction in speed of the motor atpredetermined points in the travel thereof, and means controlled andoperated by the motor for effecting an intermittent operation of each ofthe speed reducing means.

9. In a furnace hoisting apparatus, the combination with an electricmotor, of a resistance in a circuit of the motor for controlling thespeed thereof, independent means for varying said resistance. and acircuit controlling mechanism for effecting the operation of saidresistance varying means.

1.0. In a furnace hoisting apparatus, the combination with an electricmotor, of a resistance in a circuit of the motor for controlling thespeed thereof, independent means controlled by the motor for varyingsaid resistance, and a circuit controlling mechanism for said resistancevarying means.

ll. In a furnace hoisting apparatus, the combination with an electricmotor, of a. resistance in a circuit of the motor for controlling thespeed thereof, independent means controlled by the motor for varyingsaid resistance in proportion to the speed of the motor, and a circuitcontrolling mechanism for said resistance varying means.

said resistance, and a circuit controlling mechanism operated by themotor for effectingthe operation of said' resistance varying means.

13; In a furnace hoisting apparatus, the ,combination with an'electricmotor, of are- ;sistance in afield windin circuit of themoitor,electro-iesponsi\e devices fol control- .ling said resistance in,proportion to the speed of the motor, and means for energiz- -ingone'orthe other of' said-electro-responsive" devices accordingto'the directionof rotation of said=motor.

: 14: In a furnace hoisting,- apparatus, the :combination'witlranelectric motor,-of arrefsistance ina field'winding'=- circuit ofthemotor, electro-responsive devicesfor controllingsaid resistance inproportion to the a speed of the 1notor,.and means controlled by themotor for etfecting' the operation of one or the other of said electroresponsive devices according-to the direction ofrotationoftsa-id'ntotor.

, 15. In a furnace hoistingapparatus, the combination with an electricmotor, of two electro-magnets arranged to be connected lacross the motorarmature, a resistance controlled by said electro-magnets for varyingthe speed of the mot0r,,anda device controlled by the motor forlclosingthe circuit of one or the other of said electro-magnets according to thedirection of rotation of the motor.

16. In a furnace hoisting apparatus, the combination With an electricmotor, of two electro-magnets arranged to be connected across the motorarmature, a resistance in series with a field winding of the motor andcontrolled by said electro-magnets for effecting a speed reduction ofthe motor, and a device controlled by the motor for closing the circuitof one or the other of said electro-magnets according to the directionof rotation of the motor.

17. In'a furnace hoisting apparatus, the combination with an electricmotor, of means controlled by the motor for effecting a speed reductionin proportion to the load, a circuit controlling device operated by themotor for effecting the operation of said speed controlling means, andmeans for yarying the action of said speed controlling meansindependently of each other.

18. In a system of motor control for furnace hoist; skips, thecombination of an electric motor, a load carrying device operatedthereby. means to effect an automatic reduction of speed as the loadcarrying device approaches one limit of travel, and means to effect adifferent rate of speed reduction as the load carrying device approachesthe opposite limit of travel.

19. In a system of control for furnace hoist skips, the combination ofan electric motor, a load device, means connecting the motor and loaddevice for lifting and lowering the latter, a field circuit for themotor comprising sectional resistance, means for automaticallyestablishing said circuit and cutting out a portion of the resistance asthe load device approaches one limit of travel, and means to establishsaid circuit and cut out a difiercnt amount of said resistance as theload device nears the opposite limit of travel.

20. In an electric furnace hoist, the combination of an electric motor,a dynamic circuit therefor comprising a sectional resistance, anautomatic controller geared to run with the motor, an electromagnethaving its circuit extended through the controller and controlling thesaid resistance When the motor is operating in one direction, and aseparate electromagnet having its circuit extended through thecontroller and cont-rolling the resistance when the motor is operatingin the opposite direction.

21. In an electric furnace hoist, the'combination of an electric motor,resistance in a circuit of the motor, an elect-romagnet controlling saidresistance when the motor is operating in one direction, and a separateelectromagnet controlling said resistance when the motor ,is operatingin the reverse direction.

22. In an electric furnace hoist, the combination of an electric motor,a field circuit comprising sectional resistance, an automaticcontroller, elect romagnets controlling said resistance and having theircircuits extended through the controller and arranged to be closed insuccession during the opera tion of the motor in one direction, andadditional electromagncts controlling said rosistauce andvhaving theircircuits extended through the controller and arranged to be closed insuccession during the operation of the motor 111 the reverse direction.

In testimony whereof, I have signed my name to this specification in thepresence of r two subscribing Witnesses.

' FRANK I. SMITH.

Witnesses GEO. SWANSTON, SAM SCHAGREN.

